[performance] rewrite timelines to rely on new timeline cache type (#3941)

* start work rewriting timeline cache type

* further work rewriting timeline caching

* more work integration new timeline code

* remove old code

* add local timeline, fix up merge conflicts

* remove old use of go-bytes

* implement new timeline code into more areas of codebase, pull in latest go-mangler, go-mutexes, go-structr

* remove old timeline package, add local timeline cache

* remove references to old timeline types that needed starting up in tests

* start adding page validation

* fix test-identified timeline cache package issues

* fix up more tests, fix missing required changes, etc

* add exclusion for test.out in gitignore

* clarify some things better in code comments

* tweak cache size limits

* fix list timeline cache fetching

* further list timeline fixes

* linter, ssssssssshhhhhhhhhhhh please

* fix linter hints

* reslice the output if it's beyond length of 'lim'

* remove old timeline initialization code, bump go-structr to v0.9.4

* continued from previous commit

* improved code comments

* don't allow multiple entries for BoostOfID values to prevent repeated boosts of same boosts

* finish writing more code comments

* some variable renaming, for ease of following

* change the way we update lo,hi paging values during timeline load

* improved code comments for updated / returned lo , hi paging values

* finish writing code comments for the StatusTimeline{} type itself

* fill in more code comments

* update go-structr version to latest with changed timeline unique indexing logic

* have a local and public timeline *per user*

* rewrite calls to public / local timeline calls

* remove the zero length check, as lo, hi values might still be set

* simplify timeline cache loading, fix lo/hi returns, fix timeline invalidation side-effects missing for some federated actions

* swap the lo, hi values :facepalm:

* add (now) missing slice reverse of tag timeline statuses when paging ASC

* remove local / public caches (is out of scope for this work), share more timeline code

* remove unnecessary change

* again, remove more unused code

* remove unused function to appease the linter

* move boost checking to prepare function

* fix use of timeline.lastOrder, fix incorrect range functions used

* remove comments for repeat code

* remove the boost logic from prepare function

* do a maximum of 5 loads, not 10

* add repeat boost filtering logic, update go-structr, general improvements

* more code comments

* add important note

* fix timeline tests now that timelines are returned in page order

* remove unused field

* add StatusTimeline{} tests

* add more status timeline tests

* start adding preloading support

* ensure repeat boosts are marked in preloaded entries

* share a bunch of the database load code in timeline cache, don't clear timelines on relationship change

* add logic to allow dynamic clear / preloading of timelines

* comment-out unused functions, but leave in place as we might end-up using them

* fix timeline preload state check

* much improved status timeline code comments

* more code comments, don't bother inserting statuses if timeline not preloaded

* shift around some logic to make sure things aren't accidentally left set

* finish writing code comments

* remove trim-after-insert behaviour

* fix-up some comments referring to old logic

* remove unsetting of lo, hi

* fix preload repeatBoost checking logic

* don't return on status filter errors, these are usually transient

* better concurrency safety in Clear() and Done()

* fix test broken due to addition of preloader

* fix repeatBoost logic that doesn't account for already-hidden repeatBoosts

* ensure edit submodels are dropped on cache insertion

* update code-comment to expand CAS accronym

* use a plus1hULID() instead of 24h

* remove unused functions

* add note that public / local timeline requester can be nil

* fix incorrect visibility filtering of tag timeline statuses

* ensure we filter home timeline statuses on local only

* some small re-orderings to confirm query params in correct places

* fix the local only home timeline filter func

1 files changed, 198 insertions, 0 deletions

diff --git a/internal/cache/timeline/status_map.go b/internal/cache/timeline/status_map.go
new file mode 100644
index 000000000..e402883af
--- /dev/null
+++ b/internal/cache/timeline/status_map.go
@@ -0,0 +1,198 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package timeline
+
+import (
+	"maps"
+	"sync/atomic"
+)
+
+// StatusTimelines is a concurrency safe map of StatusTimeline{}
+// objects, optimizing *very heavily* for reads over writes.
+type StatusTimelines struct {
+	ptr atomic.Pointer[map[string]*StatusTimeline] // ronly except by CAS
+	cap int
+}
+
+// Init stores the given argument(s) such that any created StatusTimeline{}
+// objects by MustGet() will initialize them with the given arguments.
+func (t *StatusTimelines) Init(cap int) { t.cap = cap }
+
+// MustGet will attempt to fetch StatusTimeline{} stored under key, else creating one.
+func (t *StatusTimelines) MustGet(key string) *StatusTimeline {
+	var tt *StatusTimeline
+
+	for {
+		// Load current ptr.
+		cur := t.ptr.Load()
+
+		// Get timeline map to work on.
+		var m map[string]*StatusTimeline
+
+		if cur != nil {
+			// Look for existing
+			// timeline in cache.
+			tt = (*cur)[key]
+			if tt != nil {
+				return tt
+			}
+
+			// Get clone of current
+			// before modifications.
+			m = maps.Clone(*cur)
+		} else {
+			// Allocate new timeline map for below.
+			m = make(map[string]*StatusTimeline)
+		}
+
+		if tt == nil {
+			// Allocate new timeline.
+			tt = new(StatusTimeline)
+			tt.Init(t.cap)
+		}
+
+		// Store timeline
+		// in new map.
+		m[key] = tt
+
+		// Attempt to update the map ptr.
+		if !t.ptr.CompareAndSwap(cur, &m) {
+
+			// We failed the
+			// CAS, reloop.
+			continue
+		}
+
+		// Successfully inserted
+		// new timeline model.
+		return tt
+	}
+}
+
+// Delete will delete the stored StatusTimeline{} under key, if any.
+func (t *StatusTimelines) Delete(key string) {
+	for {
+		// Load current ptr.
+		cur := t.ptr.Load()
+
+		// Check for empty map / not in map.
+		if cur == nil || (*cur)[key] == nil {
+			return
+		}
+
+		// Get clone of current
+		// before modifications.
+		m := maps.Clone(*cur)
+
+		// Delete ID.
+		delete(m, key)
+
+		// Attempt to update the map ptr.
+		if !t.ptr.CompareAndSwap(cur, &m) {
+
+			// We failed the
+			// CAS, reloop.
+			continue
+		}
+
+		// Successfully
+		// deleted ID.
+		return
+	}
+}
+
+// RemoveByStatusIDs calls RemoveByStatusIDs() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) RemoveByStatusIDs(statusIDs ...string) {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.RemoveByStatusIDs(statusIDs...)
+		}
+	}
+}
+
+// RemoveByAccountIDs calls RemoveByAccountIDs() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) RemoveByAccountIDs(accountIDs ...string) {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.RemoveByAccountIDs(accountIDs...)
+		}
+	}
+}
+
+// UnprepareByStatusIDs calls UnprepareByStatusIDs() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) UnprepareByStatusIDs(statusIDs ...string) {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.UnprepareByStatusIDs(statusIDs...)
+		}
+	}
+}
+
+// UnprepareByAccountIDs calls UnprepareByAccountIDs() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) UnprepareByAccountIDs(accountIDs ...string) {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.UnprepareByAccountIDs(accountIDs...)
+		}
+	}
+}
+
+// Unprepare attempts to call UnprepareAll() for StatusTimeline{} under key.
+func (t *StatusTimelines) Unprepare(key string) {
+	if p := t.ptr.Load(); p != nil {
+		if tt := (*p)[key]; tt != nil {
+			tt.UnprepareAll()
+		}
+	}
+}
+
+// UnprepareAll calls UnprepareAll() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) UnprepareAll() {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.UnprepareAll()
+		}
+	}
+}
+
+// Trim calls Trim() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) Trim() {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.Trim()
+		}
+	}
+}
+
+// Clear attempts to call Clear() for StatusTimeline{} under key.
+func (t *StatusTimelines) Clear(key string) {
+	if p := t.ptr.Load(); p != nil {
+		if tt := (*p)[key]; tt != nil {
+			tt.Clear()
+		}
+	}
+}
+
+// ClearAll calls Clear() for each of the stored StatusTimeline{}s.
+func (t *StatusTimelines) ClearAll() {
+	if p := t.ptr.Load(); p != nil {
+		for _, tt := range *p {
+			tt.Clear()
+		}
+	}
+}